Hi,
A distinctive feature of reducers is that "reducing is a one-shot thing".
The common understanding is that reducers are fast for cases where you want
to process whole collection at once, but for infinite and lazy seqs, you
have to use good old seqs.
With core.async, it is now easy to create a transformation which produces
lazy seq from any reducible collection.
(defn lazy-seq*
[reducible]
(let [c (chan)
NIL (Object.)
encode-nil #(if (nil? %) NIL %)
decode-nil #(if (identical? NIL %) nil %)]
(thread
(reduce (fn [r v] (>!! c (encode-nil v))) nil reducible)
(close! c))
(take-while (complement nil?) (repeatedly #(decode-nil (<!! c))))))
(def s (lazy-seq* (clojure.core.reducers/map inc (range))))
(first s)
(take 100 s)
This approach can be also extended to produce chunked seqs and chan buffer
can also be used to further tune the performance.
JW
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